The present invention relates to a process unit, used in an image forming apparatus applying an electrophotographic system.
The image forming apparatus applying the electrophotographic system is equipped with a photosensitive member, a charging device, an exposing device, a developing device, a transferring device and a fixing device, which function to record an image on a recording paper, in an apparatus main body. The charging device electrifies the photosensitive member, and the exposing device exposes the photosensitive member and forms a latent image. The developing device forms a toner image by developing the latent image on the photosensitive member. The transferring device transfers the toner image on the photosensitive member onto the recording paper. The fixing device fixes the toner image on the recording paper.
In general terms, in the image forming apparatus, a process unit is composed of at least a photosensitive member, a charging device and a developing device. There are image forming apparatuses known in the prior-art which adopt the process unit disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-120251 and the process unit disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-317954. The former process unit is an integrated unit structure which combines a photosensitive member unit including a photosensitive member, a charging device and a developing device as one unit. The latter process unit is constructed such that a photosensitive member, a charging device and a developing device are directly integrated. In these structures, the whole process unit is integrated as one body, and when the photosensitive member, which is a consumable component, has deteriorated, the whole process unit is removed from the apparatus main body of the image forming apparatus. In short, in these structures, when the photosensitive member is to be replaced, the whole process unit (including not only the photosensitive member which is required to be replaced, but also the charging device and developing device) is replaced.
However, each of the lifetimes of the devices or components, which are included in the process unit, are not equal and are different. Although the lifetime of the photosensitive member is short by being frequently used, the lifetimes of the other devices or components, which are used less than the photosensitive member, are longer.
When the whole process unit is replaced on the basis of the lifetime of the photosensitive member, it is uneconomical to replace other devices or components whose lifetimes have not yet ended and which are still able to be used.
The purpose of the present invention is to provide a process unit which enhances the cost efficiency of replacing devices or parts by dividing the process unit into a plurality of separable units to avoid unnecessary replacement of still usable devices or parts when a device or a part whose lifetime has expired is to be replaced, as well as to provide an image forming apparatus having such a process unit.
In the present invention, a unit housing can be divided into an upper housing and a lower housing, a photosensitive member unit is removable from the upper housing, and a developing device is removable from the lower housing.
A process unit of the present invention comprises: a unit housing including a downwardly opened upper housing and an upwardly opened lower housing, the upper housing and the lower housing being detachably coupled to define a space section; a photosensitive member unit detachably attached in the upper housing, the photosensitive member unit including at least a case, a photosensitive member attached in the case, and a charging device attached in the case and charging the photosensitive member; and a developing device detachably attached in the lower housing, the developing device including at least a toner case containing toner, and a developing roller attached in the toner case and applying the toner to the photosensitive member.
An image forming apparatus of the present invention comprises: an apparatus main body; and a process unit placed in the apparatus main body, wherein the process unit comprises: a unit housing including a downwardly opened upper housing and an upwardly opened lower housing, the upper housing and the lower housing being detachably coupled to define a space section; a photosensitive member unit detachably attached in the upper housing, the photosensitive member unit including at least a case, a photosensitive member attached in the case, and a charging device attached in the case and charging the photosensitive member; and a developing device detachably attached in the lower housing, the developing device including at least a toner case containing toner, and a developing roller attached in the toner case and supplying the toner to the photosensitive member.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.